When the air-fuel mixture in the combustion chamber of an internal combustion engine is ignited, a portion of the burnt gas during the power stroke leaks between the piston and the cylinder wall into the crankcase. The need to remove this gas, commonly referred to as blowby gas, from the engine crankcase is well known. Otherwise, the blowby gas would deteriorate the quality of the lubricating oil in the crankcase and also tend to increase crankcase pressure, thereby inducing oil leakage from the crankcase. Generally, the blowby gas is vented out of the crankcase and returned to the combustion chamber through the crankcase ventilation system. However, any excess oil entrained in the blowby gas must be removed prior to introducing the blowby gas to the combustion chamber.
Typically, air-oil separators are used to remove the entrained oil. The inventors of the present invention have recognized certain drawbacks with prior art separators, however. Some prior art separators utilize a blower to impart fluid motion on the blowby gas so that the blowby gas can pass through the air-oil separator. Other prior art separators rely solely on the lubricating oil in the blowby gas impinging on the walls of a baffle. However, in these separators, an inadequate amount of entrained oil is removed.